added the following at the end of the sys.txt but nothing has changed.

[vmc_voice]
enter_script="sc_volmanager_voice"
vmc_effect=100
vmc_media=40

[volume_channels]
volumefade=3000

the problem seems to be related to iGO APP, as soon as sound from iGO app kicks in, it mutes other sound source until i switch the app.